The proposed research has three parts. The first is a study of naturally-occurring inducers of aryl hydrocarbon hydroxylase (AHH) activity. Cruciferous plants contain indoles which have inducing activity. A determination of the role of each of these indoles in AHH induction by these plants will be carried out along with work to ascertain if other compounds affecting this activity are present. Efforts will be made to identify inducers of AHH in plants other than Cruciferae. The second part is an investigation of the effects of naturally-occurring and synthetic inducers on the metabolite pattern produced by incubation of polycyclic hydrocarbon carcinogens, such as benzo(a)pyrene, with microsomes from animals to whom the inducers had been administered. The synthetic inducers include compounds whose administration results in inhibition of neoplasia from polycyclic hydrocarbon carcinogens. The third part consists of experiments in which naturally-occurring and synthetic inducers will be administered to animals that will subsequently be challenged by polycyclic hydrocarbon carcinogens. These experiments are designed to establish the relationship between alterations in microsomal metabolism of polycyclic hydrocarbons resulting from administration of inducers, and changes in the neoplastic response of animals to polycyclic hydrocarbon carcinogens. BIBLIOGRAPHIC REFERENCES: Inhibition of carcinogenic effects of polycyclic hydrocarbons by benzyl isothiocyanate and related compounds. Wattenberg, LW. J. Nat. Cancer Inst. 58, 395-398, 1977. Stimulatory effect of vegetables on intestinal drug metabolism in the rat. Pantuck, EJ, Hsiao, KC, Loub, WD, Wattenberg, LW, Kuntzman, R and Conney, AJ. J. Pharmacology and Exp. Therapeut. 198, 278-283, 1976.